diff --git a/ArmPkg/Include/AsmMacroIoLib.h b/ArmPkg/Include/AsmMacroIoLib.h
index 408b2ca280..6904bdc9b0 100644
--- a/ArmPkg/Include/AsmMacroIoLib.h
+++ b/ArmPkg/Include/AsmMacroIoLib.h
@@ -149,7 +149,7 @@ _SetPrimaryStackEnd:
 _InitializePrimaryStackLoop:          ;             \
   cmp     Tmp1, sp                    ;             \
   bls     _InitializePrimaryStackEnd  ;             \
-  str     GlobalSize, [Tmp1], #-4     ;             \
+  str     GlobalSize, [Tmp1, #-4]!    ;             \
   b       _InitializePrimaryStackLoop ;             \
 _InitializePrimaryStackEnd:
 
@@ -228,7 +228,7 @@ _SetPrimaryStackEnd:
 _InitializePrimaryStackLoop:          ;             \
   cmp     Tmp1, sp                    ;             \
   bls     _InitializePrimaryStackEnd  ;             \
-  str     GlobalSize, [Tmp1], #-4     ;             \
+  str     GlobalSize, [Tmp1, #-4]!    ;             \
   b       _InitializePrimaryStackLoop ;             \
 _InitializePrimaryStackEnd:
 
diff --git a/ArmPkg/Include/AsmMacroIoLib.inc b/ArmPkg/Include/AsmMacroIoLib.inc
index 87e497b31a..301bd890ac 100644
--- a/ArmPkg/Include/AsmMacroIoLib.inc
+++ b/ArmPkg/Include/AsmMacroIoLib.inc
@@ -113,7 +113,7 @@ _SetPrimaryStackEnd
 _InitializePrimaryStackLoop
   cmp     $Tmp1, sp
   bls     _InitializePrimaryStackEnd
-  str     $GlobalSize, [$Tmp1], #-4
+  str     $GlobalSize, [$Tmp1, #-4]!
   b       _InitializePrimaryStackLoop
 _InitializePrimaryStackEnd
   MEND